Preheat the oven to 350 degrees F (180 degrees C). Generously mist a standard Bundt pan with nonstick cooking spray.

To make the batter, sift the flour, cocoa powder, and baking powder into a large bowl and stir until well combined. Put the bananas, coffee, sugar, oil, vanilla extract, and salt in a large bowl. Mix until well combined using an electric mixer or immersion blender. Pour the wet ingredients into the dry ingredients and stir until well combined. The batter will be fairly thin and runny.

Pour the batter into the prepared pan and bake for 50 minutes, or until a toothpick inserted in the center of the cake comes out clean. Let cool in the pan for 10 minutes, then invert the cake directly onto a serving dish.

To make the fudge sauce, heat the butter in a medium saucepan over medium low heat until just melted. Add the cocoa powder and stir with a whisk until well combined. Add the powdered sugar, water, optional rum, and vanilla extract and stir almost constantly until the sauce just begins to bubble. Decrease the heat to low and cook, stirring frequently, until the sauce begins to thicken, about 15 minutes. Remove from the stove and let cool; the sauce will thicken as it cools.

When the cake has cooled and the sauce is about room temperature, pour the sauce over the cake and serve immediately.

TIP:  Be sure that the Bundt pan is generously misted with nonstick cooking spray before the batter is poured in so the cake will come out cleanly after baking.
 

Per serving: 313 calories, 4 g protein, 21 g fat (6 g sat), 32 g carbohydrates, 159 mg sodium, 74 mg calcium, 4 g fiber